Reduction of entrance and exit marks left by a substrate-processing meniscus

ABSTRACT

A proximity head for generating and maintaining a meniscus for processing a substrate is described. The proximity head includes a plurality of meniscus nozzles formed on a face of the proximity head, the nozzles being configured to supply liquid to the meniscus, a plurality of vacuum ports formed on the face of the proximity head, the vacuum ports being arranged to completely surround the plurality of meniscus nozzles, and a plurality of gas nozzles formed on the face of the proximity head, the gas nozzles at least partially surrounding the vacuum ports. The proximity head further includes means for reducing a size and frequency of entrance and/or exit marks at a leading edge and a trailing edge on the substrate by aiding and encouraging liquid from the meniscus to evacuate a gap between the substrate and the carrier.

CLAIM OF PRIORITY

This Application is a continuation-in-part application under 35 U.S.C.§120 and claims priority from U.S. patent application Ser. No.11/537,501, entitled, “Carrier For Reducing Entrance And/Or Exit MarksLeft By A Substrate-Processing Meniscus” and filed on Sep. 29, 2006.This Application is incorporated herein by reference in its entirety.

CROSS REFERENCE TO RELATED APPLICATIONS

The present Application is related to the following U.S. Patents andU.S. Patent Applications, all of which are incorporated herein byreference in their entirety: U.S. Pat. No. 6,488,040, issued on Dec. 3,2002 to De Larios, et al. and entitled, “Method And Apparatus For DryingSemiconductor Wafer Surfaces Using A Plurality Of Inlets And OutletsHeld In Close Proximity To The Wafer Surfaces;” U.S. patent applicationSer. No. 10/330,843, filed on Dec. 24, 2002 and entitled, “Meniscus,Vacuum, IPA Vapor Drying Manifold;” U.S. patent application Ser. No.10/330,897, also filed on Dec. 24, 2002, entitled, “System For SubstrateProcessing With Meniscus, Vacuum, IPA Vapor, Drying Manifold;” U.S.patent application Ser. No. 10/404,692, filed Mar. 31, 2003 andentitled, “Methods And Systems For Processing A Substrate Using ADynamic Liquid Meniscus;” and U.S. patent application Ser. No.10/817,620, which was filed on Apr. 1, 2004, entitled, “SubstrateMeniscus Interface And Methods For Operation.”

BACKGROUND

In the semiconductor chip fabrication industry, it is necessary to cleanand dry a substrate after a fabrication operation has been performedthat leaves unwanted residues on the surfaces of the substrate. Examplesof such a fabrication operations include plasma etching (e.g., tungstenetch back (WEB)) and chemical mechanical polishing (CMP). In CMP, asubstrate is placed in a holder that pushes a substrate surface againsta polishing surface. The polishing surface uses a slurry which consistsof chemicals and abrasive materials. Unfortunately, the CMP processtends to leave an accumulation of slurry particles and residues on thesubstrate surface. If left on the substrate, the unwanted residualmaterial and particles may defects. In some cases, such defects maycause devices on the substrate to become inoperable. Cleaning thesubstrate after a fabrication operation removes unwanted residues andparticulates.

After a substrate has been wet cleaned, the substrate must be driedeffectively to prevent water or cleaning fluid, (hereinafter, “fluid”)remnants from leaving residues on the substrate. If the cleaning fluidon the substrate surface is allowed to evaporate, as usually happenswhen droplets form, residues or contaminants previously dissolved in thefluid will remain on the substrate surface after evaporation and canform spots. To prevent evaporation from taking place, the cleaning fluidmust be removed as quickly as possible without the formation of dropletson the substrate surface. In an attempt to accomplish this, one ofseveral different drying techniques are employed such as spin-drying,IPA, or Marangoni drying. All of these drying techniques utilize someform of a moving liquid/gas interface on a substrate surface, which, ifproperly maintained, results in drying of a substrate surface withoutthe formation of droplets. Unfortunately, if the moving liquid/gasinterface breaks down, as often happens with all of the aforementioneddrying methods, droplets form and evaporation occurs resulting incontaminants being left on the substrate surface.

In view of the foregoing, there is a need for improved cleaning systemsand methods that provide efficient cleaning while reducing thelikelihood of marks from dried fluid droplets.

SUMMARY

Broadly speaking, the present invention fills these needs by providingvarious techniques for reduction of entrance and exit marks caused bydried fluid droplets left by a substrate-processing meniscus.

It should be appreciated that the present invention can be implementedin numerous ways, including as a process, an apparatus, a system, adevice, or a method. Several inventive embodiments of the presentinvention are described below.

In one embodiment, a proximity head for generating and maintaining ameniscus for processing a substrate is provided. The proximity headincludes a plurality of meniscus nozzles formed on a face of theproximity head, the nozzles being configured to supply liquid to themeniscus, a plurality of vacuum ports formed on the face of theproximity head, the vacuum ports being arranged to completely surroundthe plurality of meniscus nozzles. A plurality of main gas nozzles maybe formed on the face of the proximity head, the main gas nozzles atleast partially surrounding the vacuum ports. The proximity head furtherincludes means for reducing a size and frequency of entrance and/or exitmarks at a leading edge and a trailing edge on the substrate by aidingand encouraging liquid from the meniscus to evacuate a gap between thesubstrate and the carrier.

In another embodiment, a method for processing a substrate using ameniscus formed by upper and lower proximity heads is provided. In themethod the substrate is placed on a carrier, which is passed through ameniscus generated between upper and lower proximity heads. The carrierhas an opening sized for receiving the substrate and a plurality ofsupport pins for supporting the substrate within the opening, theopening being slightly larger than the substrate such that a gap existsbetween the substrate and the opening. Each of the upper and lowerproximity heads include a plurality of meniscus nozzles formed on a faceof the proximity head, the nozzles being configured to supply liquid tothe meniscus; a plurality of vacuum ports formed on the face of theproximity head, the vacuum ports being arranged to completely surroundthe plurality of meniscus nozzles; and a plurality of main gas nozzlesformed on the face of the proximity head, the main gas nozzles at leastpartially surrounding the vacuum ports. The method further includes astep for reducing a size and frequency of at least one of entrance orexit marks on substrates by encouraging liquid from the meniscus toevacuate the gap using the upper and lower proximity heads.

Since introduction by the present Assignee of the use of a movingmeniscus generated by a proximity head for use in cleaning, processing,and drying semiconductor wafers, it has become possible to wet and dry asubstrate with a very low risk of droplets forming on the substratesurface. This technology has been very successful at preventing anydroplets from being left on the active device region of the wafer afterthe meniscus is removed. However, the meniscus does occasionally tend toleave a small droplet at the entrance and exit points at the leading andtrailing edges of the substrate on the exclusion zone as the substratepasses through the meniscus. The exclusion zone is a margin that extendsfrom the active device region to the edge of the substrate, wheremicroelectronic structures are not formed. On occasion, entrance andexit marks can become mains surface marks, especially on hydrophilicwafers. Therefore, it is preferable that instances of such entrance andexit marks are reduced or eliminated.

The advantages of the invention will become apparent from the followingdetailed description, taken in conjunction with the accompanyingdrawings, illustrating by way of example the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be readily understood by the followingdetailed description in conjunction with the accompanying drawings, andlike reference numerals designate like structural elements.

FIG. 1 shows a perspective view of an exemplary implementation of aproximity head apparatus.

FIG. 2 shows a schematic representation of an upper proximity head.

FIGS. 3A, 3B, 3C, and 3D illustrate a substrate exiting a meniscusgenerated by upper and lower proximity heads.

FIG. 4 shows a perspective view of a gap between a carrier and asubstrate.

FIG. 5 shows a cross section view of a meniscus as it is completingtransition onto a carrier.

FIG. 6A shows a top view of the lower proximity head having means forreducing entrance and exit mark size and frequency.

FIGS. 6B, 6C, and 6D illustrate various meniscus protrusion sizes andshapes.

FIG. 7 shows a plan view of a carrier, substrate, and meniscusperimeter.

FIGS. 8A, 8B, and 8C show an exemplary embodiment of a proximity headhaving means for reducing entrance and exit mark size and frequency.

FIGS. 9A and 9B show an exemplary embodiment of a proximity head havingmeans for reducing entrance and exit mark size and frequency.

FIG. 10 shows another embodiment of a proximity head having means forreducing entrance and exit mark size and frequency.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention.However, it will be apparent to one skilled in the art that the presentinvention may be practiced without some of these specific details. Inother instances, well known process operations and implementationdetails have not been described in detail in order to avoidunnecessarily obscuring the invention. The term, “meniscus,” as usedherein, refers to a volume of liquid bounded and contained in part bysurface tension of the liquid. The meniscus is also controllable and canbe moved over a surface in the contained shape. In specific embodiments,the meniscus is maintained by the delivery of fluids to a surface whilealso removing the fluids so that the meniscus remains controllable.Furthermore, the meniscus shape can be controlled by precision fluiddelivery and removal systems that are in part interfaced with acontroller a computing system, which may be networked.

FIG. 1 is a perspective view of an exemplary implementation of aproximity head apparatus 100. In this example, substrate 160 ispositioned within a carrier 150 which passes between upper proximityhead 110 and lower proximity head 120 in the direction of arrow 152.Upper and lower proximity heads 110, 120, form a meniscus of fluidbetween them. Carrier 150 may be connected to some apparatus (not shown)for causing carrier 150 to move between upper and lower proximity heads110, 120 in the direction of arrow 166. In one embodiment, a substrate160 is deposited on carrier 150 at a first location on one side ofproximity heads 110, 120, and removed when carrier 150 arrives at asecond location on an opposite side of proximity heads 110, 120. Carrier150 may then pass back through proximity heads 110, 120, or over, under,or around proximity heads 110, 120, back to the first location, where anext substrate is deposited, and the process is repeated.

It should be noted that, while in the example shown in FIG. 1, thesubstrate moves through proximity heads 110, 120 in the direction ofarrow 152, it is also possible for the substrate to remain stationarywhile the proximity heads 110, 120, pass over and under the substrate,so long as the substrate moves with respect to the proximity heads.Furthermore, the orientation of the substrate as it passes between theproximity heads is arbitrary. That is, the substrate is not required tobe oriented horizontally, but can instead be vertically oriented or atany angle.

In certain embodiments, a controller 130, which may be a general purposeor specific purpose computer system whose functionality is determined bylogic circuits or software, or both, controls the movement of carrier150 and the flow of fluids to upper and lower proximity heads 110, 120.

FIG. 2 shows a schematic representation of upper proximity head 110.Proximity head includes a plurality of central meniscus nozzles 116formed in face 111 of proximity head 110 through which a liquid issupplied that forms meniscus 200. The liquid may be deionized water, acleaning solution, or other liquid designed to process, clean, or rinsesubstrate 160. A plurality of ports 114 apply a vacuum at a perimeter ofmeniscus 200. Vacuum ports 114 aspirate liquid from meniscus 200 andsurrounding fluid, such as air or other gas supplied by main gas nozzles112. In certain embodiments, main gas nozzles 112 surround vacuum ports114 and supply isopropyl alcohol vapor, nitrogen, a mixture thereof, orother gas or gasses or gas/liquid fluids. Depending on theimplementation, main gas nozzles 112 and fluid supplied therefrom may beprovided to aid in maintaining a coherent liquid/gas interface at thesurface of meniscus 200. In one embodiment, main gas nozzles 112 areabsent or are not used. In another embodiment, main gas nozzles 112supply carbon dioxide (CO₂) or a mixture of N₂ and isopropyl alcohol(IPA) vapor. The lower proximity head 120, not shown in FIG. 2, may beprovided as a mirror image to the upper proximity head, and may operatein a similar manner. More details relating to proximity head structureand operation are incorporated by reference in the Cross Reference toRelated Art section above. In particular, U.S. patent application Ser.Nos. 10/261,839, 10/330,843, and 10/330,897 are referenced foradditional details relating to proximity head structure and operation.

FIGS. 3A through 3D illustrate a substrate 160 exiting meniscus 200generated by upper and lower proximity heads 110, 120. In FIG. 3A,substrate 160 extends all the way through meniscus 200 such that itsleading edge 162 and trailing edge 164 lie on opposite sides of meniscus200. It should be noted that, typically, substrate 160 will be circularand while carrier 150 is shown outside of meniscus 200, parts of carrier150 may be in contact with meniscus 200, although not visible in thisFigure.

In FIG. 3B, meniscus 200 is transitioning from substrate 160 to carrier150. Carrier 150 may be slightly thicker in cross section than substrate160. For example, substrate 160 may be about 0.80 mm thick whereas thecarrier may be about 1.5 mm thick. Thus, as meniscus 200 transitionsonto carrier 150, a certain amount of meniscus liquid is displaced bycarrier 150.

In FIG. 3C, meniscus 200 is transitioning completely off substrate 160and onto carrier 150. At this time, the trailing edge of meniscus 200 isstill in contact with trailing edge 164 of substrate 160. Forces actingon meniscus 200 at this point in time is described with reference toFIG. 5 below.

In FIG. 3D, the meniscus has completely transitioned off of substrate160, leaving a small droplet 202 of meniscus liquid on the exclusionzone of substrate 160 at the trailing edge 164 of substrate 160. Droplet202, if allowed to dry can leave a spot formed of dissolved or entrainedelements, the spot being referred to herein as an exit mark. If thesubstrate surface is hydrophilic, droplet 202 can migrate to the activedevice region of the substrate, which can cause defects in devicesformed thereon. A number of factors are believed to contribute to thepresence and size of small droplet 202 at the trailing edge 164 ofsubstrate 160. It should be noted that an entrance mark at leading edge162 can be formed in a similar manner as leading edge 162 exits meniscus200.

FIG. 4 shows a perspective view of a gap 158 between a carrier 150 and asubstrate 160. Meniscus perimeter 204 shows the area of contact of themeniscus with carrier 150 and substrate 160. The meniscus is travelingin the direction indicated by arrow 208. As the meniscus transitions offof waver 160, meniscus fluid in gap 158 is swept by the edge of themeniscus along the direction of arrows 206. As the trailing edge 210 ofmeniscus perimeter 204 reaches trailing edge 164 of substrate 160, fluidis directed toward a point 212 in gap adjacent to the substrate'strailing edge 164. It should be recognized that fluid in gap 158 isconstantly flowing out of gap 158 as the meniscus transitions ontocarrier 150. Therefore, the fluid is not expected to literally followarrows 206, but rather that a vector component of the direction of flowlies on arrows 206, resulting in a build-up of fluid at point 212.

FIG. 5 shows a cross section view of meniscus 200 at point 212 as it iscompleting transition onto carrier 150. At this point, meniscus 200 isstill attached to trailing edge 164 of substrate 160. Carrier 150 may besomewhat thicker than substrate 160, inhibiting the flow of liquid awayfrom substrate 160 along arrows 214. Vacuum ports 114 draw fluidincluding meniscus liquid and surrounding gas, exerting a force onmeniscus liquid indicated by arrows 216. An additional force may beexerted by fluid exiting main gas nozzles 112 (FIG. 2) which, ifprovided, push inward against the gas/liquid interface of meniscus 200as shown by arrows 218. A gravitational force 221 is also exertedagainst meniscus 200. And, if substrate 160 is hydrophilic, then anattraction to meniscus liquid can cause hydrogen bonding forces to pullwater back onto substrate 160, as represented by arrows 222.

FIG. 6A shows a face 121 of lower proximity head 120 having means forreducing entrance and exit mark size and frequency by enhancing the flowof meniscus liquid from the carrier-substrate gap as the meniscustransitions off of the substrate. As described above with reference toFIG. 2, lower proximity head 120 includes a plurality of centrallydisposed meniscus nozzles 116 for supplying meniscus liquid, a pluralityof vacuum ports 114 disposed so that they completely surround meniscusnozzles 116. Vacuum ports 114 aspirate meniscus liquid and surroundinggas. Optionally, a plurality of main gas nozzles 112 at least partiallysurround vacuum ports 114 and supply a gas or gas/liquid mixture to helpmaintain the integrity of the gas/liquid interface of the meniscus.Meniscus nozzles 116, vacuum ports 114, and, optionally, main gasnozzles 112 are formed in face 121 of proximity head 120. In oneembodiment, a means for reducing the size and frequency of entrance andexit marks is provided by a centrally located protrusion on the trailingside 122 of the meniscus. The arrangement of vacuum ports 114 determinesthe shape of the meniscus. FIG. 6 shows lower proximity head 120 formingthe centrally located protrusion by positioning vacuum ports 114 andadjacent main gas nozzles 112 farther from an axis defined by meniscusnozzles 116 at a center portion 125 of lower proximity head 120. Acorresponding central protrusion is formed on an upper proximity head110 (FIG. 1) so that they both generate a centrally located meniscusprotrusion on the trailing side of the meniscus.

FIG. 6B shows an outline of exemplary meniscus configuration formed bythe proximity head of FIG. 6A. The meniscus includes a main portion 225and a protrusion 220. The protrusion 220 may have various shapes. Forexample, as shown in FIG. 6C, the protrusion 220A has straight leading,the protrusion 220B has two convex leading edges extending smoothly fromthe meniscus to a central point, the protrusion 220C has concave leadingedges, and the protrusion 220D has a complex leading edge shape. In oneembodiment, the leading edges are concave as presented in 220C, with theleading edges having the same radius of curvature as the substrate 160(FIG. 7).

In FIG. 6C, a minimum protrusion size is shown having a protrusionextension 224 equal to the distance between two adjacent vacuum portsand a protrusion width 226 equal to the distance between three adjacentvacuum ports. However, the protrusion can be of any suitable size. Inone embodiment, for example, the protrusion has an extension equal to alength defined by the distance of 6 adjacent vacuum ports and a widthdefined by the distance of 12 vacuum ports, with each vacuum port beingabout 0.06 inches in diameter and having a 0.12 inch pitch(center-to-center spacing).

FIG. 7 shows a plan view of carrier 150, substrate 160, and meniscusperimeter 204 at a first position 230 and at a second position 232.Carrier 150 moves in a direction indicated by arrow 166 and/or meniscusmoves in a direction indicated by arrow 208. Carrier 150 includes aplurality of support pins 152, each having substrate support andcentering features (not shown), to ensure a uniform substrate-carriergap 158 between substrate 160 and carrier 150. In one embodiment,carrier 150 has sloped edges at the leading side 154 and trailing side156 to prevent abrupt changes in the volume of meniscus liquid ascarrier 150 enters and exits the meniscus. For example, carrier 150 hassix sides with two leading edges 155 each at an angle θ from transverseand together forming a centrally-located point, and correspondingtrailing edges 159 each forming an angle θ to the transverse directionand together forming a centrally-located point. In one embodiment, θ isabout 15 degrees. Other shapes that don't result in a rapid displacementof meniscus liquid are also possible, such as a trapezoid orparallelogram, wherein leading and trailing edges are at an angle otherthan a right angle to the direction of travel of the carrier or are atan angle to (i.e., not parallel with) the leading and trailing edges ofthe meniscus.

At a certain point in time, the meniscus is located at position 230 andtraveling in a direction 208 with respect to carrier 150. At a latertime, the meniscus is located at position 232. At position 232,protrusion 220 extends across gap 158. Because of protrusion 220, thetrailing edge 210 of meniscus perimeter 204 is not a straight linetangent to gap 158. As a result, fluid exiting point 212 (FIG. 4) hasadditional time to escape from gap 158 due to the presence of protrusion220. Since the fluid has additional time to escape from gap 158, it isless likely to remain attached to substrate 160 and leave a mark.

Protrusion 220 can also be effective in reducing an entrance mark formedat a leading edge 162 of substrate 160. In one embodiment, acentrally-located indentation is formed on the leading edge of themeniscus (not shown) to further reduce instances of entrance marks. Itshould be noted that the shape of protrusion 220, including the width ofprotrusion 220 and the depth of protrusion 220, that is the amount ofextension of protrusion 220, may vary depending on implementation, butin one embodiment, is sufficiently narrow and provides sufficientextension to improve the flow of meniscus liquid from thecarrier-substrate gap.

FIGS. 8A, 8B, and 8C show an exemplary embodiment of a proximity head250 having means for reducing entrance and exit mark size and frequencyby enhancing the flow of meniscus liquid from the carrier-substrate gapas the meniscus transitions off of the substrate. In particular,proximity head 250, which can be an upper or lower proximity head,includes centrally disposed gap evacuation gas nozzles 252 formed onface 251 to provide additional supply of gas to push against meniscus200 as it transitions completely off of substrate 160, as best seen inFIG. 8C. As mentioned above with reference to FIG. 5, the meniscustouching substrate 160 and substrate-carrier gap 158 is subject tocompeting forces, including surface tension forces that both draw themeniscus onto the substrate and inhibit transitioning onto the carrier,suction forces drawing the meniscus off of both the substrate andcarrier, and gravity, which pulls the meniscus liquid intosubstrate-carrier gap 158. In addition, a gas flow can exert positivepressure on meniscus 200, and therefore help counter surface tensionforces which can result in entrance and exit marks. Main gas nozzles 112deliver carbon dioxide or nitrogen and/or isopropyl alcohol vapor to themeniscus to aid in meniscus containment and wafer drying. However, maingas nozzles 112 cannot readily be used to aid in entrance and exit markelimination because main gas nozzles 112, which are arranged around atleast a portion of vacuum ports 114, affect the entire meniscus, or asubstantial volume thereof. One or more gap evacuation gas nozzles 252,on the other hand, provide a localized “fan,” or “curtain” of gas flow,which can be independently controlled, and therefore be selectivelyapplied to the substrate/meniscus interface only in the areas ofentrance and exit mark formation. By applying additional pressureagainst meniscus 200 just as the trailing edge of meniscus 200transitions on or off of substrate 160 using gap evacuation gas nozzles252 meniscus liquid exiting gap 158 is pushed back into the meniscus sothat it does not stick to the wafer, thereby reducing the size andlikelihood of entrance and exit mark formation, and prevent waferdefects.

In certain embodiments, a plurality of central fluid port zones providefor additional pressure during just prior and during transition by thetrailing edge of the meniscus between substrate 160 and carrier 150. Inthis embodiment, one or more centrally disposed gap evacuation gasnozzles 252 are surrounded by one or more additional zones tertiarynozzles 254, visible in FIGS. 8A and 8B. Any number of zones can beprovided, each being independently controlled by controller 130 (FIG. 1)to supply gas pressure against meniscus 200 at appropriate times duringmeniscus transition. Controller 130 may include a mechanical or computerinitiated timing mechanism. For example, a mechanical timing mechanismmay employ a proximity sensor (not shown) to activate gap evacuation gasnozzles 252 (or gap evacuation gas nozzles 252 and secondary gapevacuation nozzles 254), wherein the proximity sensor responds to aposition of carrier 150 with respect to upper and lower proximity heads110, 120 (FIG. 1). A computer initiated timing mechanism may includeposition information from a robotic actuating mechanism (not shown) usedto convey carrier 150 through the meniscus.

FIGS. 9A and 9B show an exemplary embodiment of a proximity head 260having means for reducing entrance and exit mark size and frequency byenhancing the flow of meniscus liquid from the carrier-substrate gap asthe meniscus transitions off of the substrate. In particular, proximityhead 260 includes a partitioned vacuum manifold to provide a pluralityof vacuum port zones, each connected to an independent vacuum source. Byproviding an independent vacuum source to a central zone 262, which hasvacuum ports formed into face 216 at a location corresponding to thetrailing edge of the meniscus, vacuum shunting is minimized, whichenhances flow of meniscus liquid exiting the carrier-substrate gap 158.

Vacuum shunting occurs when a few vacuum ports are overrun with liquid.In such cases, the pressure drop across faceplate 265 (FIG. 9A) may beinsufficient to clear the liquid, causing gasses and fluid from themeniscus to divert to nearby vacuum ports. When a significant volume ofwater is trapped between the wafer and carrier, vacuum shunting canoccur just as the meniscus is transitioning completely off thesubstrate. This reduces the available suction at the exact spot where ismost needed: at the trailing edge of the substrate as the substrateexits the meniscus. This reduced availability of vacuum can thereforereduce the removal of liquid from the substrate-carrier gap, which canlead to exit mark formation. A similar effect can occur at the leadingedge of the substrate, which can cause an entrance mark to form.

By providing an independent vacuum source to a central zone 262 ofvacuum ports centrally positioned on the trailing edge of the meniscus,vacuum shunting is minimized, which enhances flow of meniscus liquidexiting the carrier-substrate gap 158.

Referring to FIGS. 9A and 9B, a plurality of meniscus nozzles 116 formedinto face 261 provide meniscus liquid to the meniscus 200 (FIG. 2).Surrounding meniscus nozzles 116 are vacuum ports 114, which aspirate amixture of meniscus liquid and surrounding gas. At least partiallysurrounding vacuum ports 114, main gas nozzles 112 may be provided tosupply gas or gas/liquid mixture, which can aid in maintaining meniscusintegrity. In one embodiment, vacuum ports 114 are divided into aplurality of zones, including a first zone 262 centrally disposed alongthe trailing edge 204 of proximity head 260 and at least one additionalzone 263, 264 comprising the remaining vacuum ports 114. The additionalzone(s) can include a secondary zone 264 comprising a plurality ofvacuum ports 114 on either side of first zone 262, and tertiary zone 263comprising the remaining vacuum ports 114. Each zone 263, 262, 264 has acorresponding dedicated, independent manifold 271, 272, 274, and eachmanifold 271, 272, 274, is in fluid communication with a correspondingconnection 281, 282, 284 to a vacuum source 280.

FIG. 10 shows another embodiment of a proximity head having means forreducing entrance and exit mark size and frequency by enhancing the flowof meniscus liquid from the carrier-substrate gap as the meniscustransitions off of the substrate. Proximity head 290 includes aplurality of meniscus nozzles 116 formed into face 291 for supplyingmeniscus liquid. Surrounding meniscus nozzles 116 on face 291 is aplurality of vacuum ports 114 for aspirating meniscus liquid andsurrounding gases. Vacuum ports 114 includes a first row 293 of vacuumports 114 that completely surrounds meniscus nozzles 116 and row 295 ofvacuum ports 114 adjacent a central portion of the trailing edge 298 ofproximity head 290. Vacuum ports 114 lying in first row 293 areconnected to a common manifold as described above for zone 263 in FIG.9A. Vacuum ports 114 lying in second row 295 are connected to one of oneor more additional manifolds. In one embodiment, ports 114 in row 295 atzone 292 centrally disposed on the trailing side of proximity head 290are connected to one manifold (not shown), and ports 114 in row 295 inzones 294 are connected to another manifold (not shown). Each manifoldincludes an independent connection to a vacuum source as described abovewith reference to FIG. 9A.

It should be noted that either or both the upper and lower proximityheads and the carrier can be controlled by a computer system such thatthe rate of travel of the carrier with respect to the proximity headsmay be constant or vary depending on the position of the carrier withrespect to the proximity heads. In some embodiments, for example, therate of travel of the carrier may be slower as the meniscus transitionson and off the substrate, thereby providing additional time for meniscusliquid to be flow out of the carrier-substrate gap. In addition, the gasflow through gas nozzles 112, 252 (FIG. 8C) and vacuum supplied tovacuum ports 114 (FIGS. 9A-10) can be mechanically and/or computercontrolled, either to time the activation/deactivation of suction, or tovary the flow rates depending on the relative position of the carrierwith respect to the proximity heads. The computer control can beimplemented using hardware logic or in conjunction with a multipurposecomputer processor, using a computer program written to control themovement and/or application of suction. In certain embodiments, acomputer program also controls the volume and/or constituents of fluidsupplied to the meniscus. Therefore, the computer program can definefluid recipes specifically tailored to each of a plurality of givenapplications.

With the above embodiments in mind, it should be understood that theinvention can employ various computer-implemented operations involvingdata stored in computer systems. These operations are those requiringphysical manipulation of physical quantities. Usually, though notnecessarily, these quantities take the form of electrical or magneticsignals capable of being stored, transferred, combined, compared andotherwise manipulated. Further, the manipulations performed are oftenreferred to in terms such as producing, identifying, determining, orcomparing.

Any of the operations described herein that form part of the inventionare useful machine operations. The invention also relates to a device oran apparatus for performing these operations. The apparatus can bespecially constructed for the required purpose, or the apparatus can bea general-purpose computer selectively activated or configured by acomputer program stored in the computer. In particular, variousgeneral-purpose machines can be used with computer programs written inaccordance with the teachings herein, or it may be more convenient toconstruct a more specialized apparatus to perform the requiredoperations.

The invention can also be embodied as computer readable code on acomputer readable medium. The computer readable medium is any datastorage device that can store data, which can be thereafter be read by acomputer system. The computer readable medium also includes anelectromagnetic carrier wave in which the computer code is embodied.Examples of the computer readable medium include hard drives, networkattached storage (NAS), read-only memory, random-access memory, CD-ROMs,CD-Rs, CD-RWs, magnetic tapes and other optical and non-optical datastorage devices. The computer readable medium can also be distributedover a network-coupled computer system so that the computer readablecode is stored and executed in a distributed fashion.

Embodiments of the present invention can be processed on a singlecomputer, or using multiple computers or computer components which areinterconnected. A computer, as used herein, shall include a standalonecomputer system having its own processor(s), its own memory, and its ownstorage, or a distributed computing system, which provides computerresources to a networked terminal. In some distributed computingsystems, users of a computer system may actually be accessing componentparts that are shared among a number of users. The users can thereforeaccess a virtual computer over a network, which will appear to the useras a single computer customized and dedicated for a single user.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalents of the appended claims.

1. A proximity head for generating and maintaining a meniscus forprocessing a substrate, the substrate being supported by a carrier, thecarrier comprising a frame surrounding the substrate, the proximity headcomprising: a plurality of meniscus nozzles formed in a spaced apartrelationship along a linear axis on a face of the proximity head, themeniscus nozzles configured to supply meniscus liquid to the meniscus; aplurality of vacuum ports formed in a spaced apart relationship on theface of the proximity head, the plurality of vacuum ports arranged toform a suction region that completely and contiguously surrounds theplurality of meniscus nozzles, wherein a portion of the plurality ofvacuum ports located at a central region along a trailing side of thelinear axis along which the plurality of meniscus nozzles are formed,are positioned farther away from the linear axis relative to a remainderof the plurality of vacuum ports present on the trailing side of thelinear axis, such that an increased spacing exists between the portionof the plurality of vacuum ports at the central region and the pluralityof meniscus nozzles along the linear axis relative to a spacing thatexists between the remainder of the plurality of vacuum ports present onthe trailing side of the linear axis and the plurality of meniscusnozzles along the linear axis, wherein the increased spacing between theportion of the plurality of vacuum ports at the central region and theplurality of meniscus nozzles along the linear axis reduces a size and afrequency of at least one of entrance or exit marks at a leading edgeand a trailing edge on the substrate, thereby aiding and encouragingliquid from the meniscus to evacuate a gap between the substrate and thecarrier.
 2. The proximity head of claim 1, further comprising aplurality of gas nozzles formed on the face of the proximity head, thegas nozzles at least partially surrounding the plurality of vacuumports.
 3. The proximity head of claim 1, wherein the increased spacingbetween the portion of the plurality of vacuum ports at the centralregion and the plurality of meniscus nozzles along the linear axiscauses liquid from the meniscus to exit the gap as the leading edge ofthe substrate exits a trailing edge of the meniscus, thereby reducingthe size and frequency of entrance marks.
 4. The proximity head of claim1, wherein the increased spacing between the portion of the plurality ofvacuum ports at the central region and the plurality of meniscus nozzlesalong the linear axis causes the meniscus to have a protrusion on thetrailing side of the meniscus, the protrusion being centrally disposedfor evacuating fluid at the leading and trailing edges of the substrate.5. The proximity head of claim 4, wherein a shape of the protrusioncomprises two concave edges extending out from the trailing edge to acentral point.
 6. The proximity head of claim 1, wherein the proximityhead comprises at least one gap evacuation gas nozzle centrally disposedon a trailing side of the proximity head, wherein the at least one gapevacuation gas nozzle is in fluid communication with a gas supplyconnection for supplying gas, the at least one gap evacuation gas nozzlebeing configured to supply a stream of gas exerting a force againstliquid exiting the gap off the substrate and back into the meniscus. 7.The proximity head of claim 6, wherein the at least one secondary gasnozzle is arranged adjacent a plurality of main gas nozzles formed onthe face of the proximity head, the main gas nozzles at least partiallysurrounding the vacuum ports, the at least one gap evacuation gas nozzlebeing in fluid communication with a gas supply connection for supplyinggas independently from the plurality of main gas nozzles.
 8. Theproximity head of claim 6, further comprising at least one plurality ofsecondary gap evacuation nozzles, each plurality of secondary gapevacuation nozzles being disposed on either side of the at least one gapevacuation nozzle, each plurality of secondary gap evacuation nozzlesbeing in fluid communication with a corresponding connection forsupplying gas independently of the at least one gap evacuation nozzle.9. The proximity head of claim 1, wherein the proximity head comprises adivision of the plurality of vacuum ports into a plurality of zones, theplurality of zones including at least a central zone located on atrailing side of the face of the proximity head, each of the pluralityof zones including a corresponding independent vacuum connection influid communication with the vacuum ports of the zone.
 10. The proximityhead of claim 9, wherein the plurality of zones includes a secondaryzone comprise all the vacuum ports not of the central zone.
 11. Theproximity head of claim 9, wherein the plurality of zones includes asecondary zone comprising vacuum ports positioned on either side of thecentral zone, and a tertiary zone comprising all the vacuum ports not ofthe central zone or the secondary zone.
 12. The proximity head of claim9, wherein the central zone comprises a single row of vacuum ports andthe plurality of zones includes secondary zone comprising a row ofvacuum ports along the central zone.
 13. A proximity head for generatingand maintaining a meniscus for processing a substrate, the substratebeing supported by a carrier, the carrier comprising a frame surroundingthe substrate, the proximity head comprising: a plurality of meniscusnozzles formed along a linear axis on a face of the proximity head, themeniscus nozzles being configured to supply meniscus liquid to themeniscus; a plurality of vacuum ports formed on the face of theproximity head, the plurality of vacuum ports arranged to form a suctionregion that completely and contiguously surrounds the plurality ofmeniscus nozzles, wherein a portion of the plurality of vacuum portslocated at a central region along a trailing side of the linear axisalong which the plurality of meniscus nozzles are formed, are positionedfarther away from the linear axis relative to a remainder of theplurality of vacuum ports present on the trailing side of the linearaxis, such that the suction region at the central region along thetrailing side of the linear axis extends in a mirrored concave shapeaway from the linear axis to a point at a midpoint of the centralregion; a plurality of gas nozzles formed on the face of the proximityhead, the gas nozzles at least partially surrounding the plurality ofvacuum ports; and wherein the mirrored concave shape of the suctionregion at the central region along the trailing side of the linear axisreduces a size and a frequency of at least one of entrance and exitmarks at a leading edge and a trailing edge on the substrate, therebyaiding and encouraging liquid from the meniscus to evacuate a gapbetween the substrate and the carrier.